Steam conversion valve



y 1964 w. PONTOW ETAL 3,134,827

- STEAM CONVERSION VALVE Filed D90. 23, 1959 2 Sheets-Sheet 1 y 6, 1964 w. PONTOW ETAL 3,134,827

STEAM CONVERSION VALVE Filed Dec. 23, 1959 2 Sheets-Sheet 2 United States Patent ()fiice 3,134,827 Patented May 26, 1964 3,134,827 STEAM CONVERSION VALVE Werner Pontow and Richard Oertel, Erlangen, Germany,

assignors to Siemens-Schucitertwerke Aktiengesellschaft, Beriin-Siernensstadt, Germany, a corporation of Germany Filed Dec. 23, 1959, Ser. No. 861,513 Claims. ((11. 26116) Our invention relates to steam conversion valves for simultaneously pressure-reducing and de-su-perheating steam under high pressure.

Conversion valves of this type are known from US.

Patent 2,725,221, French Patent 1,065,108 and British Patent 710,069. Such valves have bores for supplying water to be atomized within the valve space. Located on the downstream side of the valve seat is a throttle passage surrounded by an annular channel which is connected with a water supply line and communicates through the above-mentioned bores with a valve location between the valve seat and the throttle passage. In lieu of a multiplicity of bores, a suitable annular slot may serve for supplying the water to be atomized. The fact that the water passes into the internal valve space between valve seat and throttle passage renders such valves distinct from other known types of de-superheating valves. In contrast to conversion valves to which water is supplied in or behind the zone of maximum steam velocity, the in: jection of water ahead of the throttle zone, and hence ahead of the zone of greatest steam velocity, has the advantage that the pressure drop, which occurs between the initial pressure and the ultimate throttle pressure and which constitutes a power loss, is utilized to an appreciable extent for furnishing the power required for atomizing the Water. As a result, a reduction of the water into extremely fine particles is secured regardless of variations in steam throughput quantity.

' It is an object of our invention to make conversion valves of the above-mentioned type suitable for converting an additional supply of low-pressure steam to a higher pressure and, if desired, to also cool such additional steam supply, while simultaneously performing the abovementioned functions of pressure-reducing and cooling hot steam of high pressure. Such a conversion of low-pressure steam to a higher pressure is desirable in numerous steam power plants where tapped or bleeder steam, avail able from turbines, possesses too low a pressure for a particular use intended.

According to the invention, the steam conversion valve serving for simultaneously reducing and cooling highpressure steam as described above or in a similar manner, is designed as an ejector valve to whose ejectornozzle portion the de-superheated high-pressure steam is supplied together with the additional supply of lowpressure steam.

According to another feature of our invention, the valve seat and valve cone of the conversion valve is given a nozzle-shaped design so that the throttle energy of the fresh steam to be reduced in pressure is utilized, on the one hand, for finely distributing at best possible ellicacy the cooling water being supplied and, on the other hand for increasing the pressure of the low-pressure steam with a satisfactory degree of efliciency.

The above-mentioned objects, advantages and features of our invention, said features being set forth with particularity in the claims annexed hereto, will be apparent from, and will be mentioned in, the following with reference to the embodiments of conversion valves according to the invention illustrated by way of example on the accompanying drawings in which:

FIG. 1 is a schematic circuit diagram of a steam power plant provided with a steam conversion ejector valve according to the invention.

FIG. 2 is a sectional view of a conversion valve.

FIGS. 3 and 4 are partial and sectional views of two other embodiments respectively of such a valve.

FIG. 5 is a sectional view of part of a fourth embodiment of the valve; and

FIG. 6 is a partly sectional top view of FIG. 5.

The circuit diagram shown in FIG. 1 relates to a plant in which a conversion valve is used in combination with steam supplied from uncontrolled tap lines of turbines, and serves for further elucidating the objectives of the present invention.

A boiler 1 with a superheater 2 furnishes fresh steam into a steam line 3 at about 40 atmospheres and a temperature of 470 C. In a counter-pressure turbine 4 the steam taken from line 3 is reduced to a pressure of approximately 5 atmospheres. The turbine is provided with two tap outlets 5 and 6 which supply steam to a consumer line 7 required to have a pressure of 12 atmospheres. The steam-consumer line 7 is normally supplied from several tap outlets, namely in the illustrated case from the two tap lines 5 and 6 connected with the turbinedrum and turbine-wheel space respectively.

When the turbine operates under high load, an outputpressure regulator 8 keeps a regulating valve 9 in the throttle position required for maintaining the pressure in the consumer line 7 at the desired datum value. When the turbine load drops and the steam supply from drum tap line 6 no longer suffices for meeting the steam consumption in line 7, the pressure regulator 8 switches over to a regulating valve '19 and closes the valve 9. When the valve 10 is likewise regulated to fully open position and the turbine load decreases to a further extent, the valve device 11 is put into operation. This device is a steam-converting ejector operating under control by the regulator 8. The steam conversion-ejector valve 11 now adds fresh steam from line 3 to line 7. The flow energy of the fresh steam then converts a certain portion of the tap-line steam to the pressure of the consumer line 7 even if the tap-pressure should further decrease.

Further shown in FIG. 1 are the following conventional plant components. Denoted by d is a Venturi-nozzle and pressure measuring location. A steam quantity meter is denoted by e, a pressure and temperature measuring device in the drum-tap line by f, a fresh-steam pressure and temperature measuring device by g. Further provided are a pressure measuring device h for the consumer line, a temperature measuring device i for the consumer line, a temperature regulator l and a counter-pressure regulator in. Details of the ejector-type conversion valve 11 will be described presently with reference to the embodiments illustrated in FIGS. 2 to 6.

Referring to FIG. 2, the fresh steam (from line12 in FIG. 1) is supplied to a first steam-inlet duct of the valve in the direction indicated by an arrow 50. The steam entering under high pressure and at high temperature is reduced in a nozzle passage 21 when the disc and cone 20 of the valve are lifted to open position. The necessary quantity of cooling water is supplied through an annular slot 22 slightly ahead of the narrowest nozzle cross section. The cooling water passes in the direction of the arrow 23 through a water supply duct 24 into an annular channel 25 extending in the valve-seat structure around the throttle passage 21, the channel 25 communicates with the valve space through the above-mentioned narrow slot at a location where the nozzle cross-section of passage 21 does not yet have its narrowest dimension.

The steam outlet duct of the valve is formed by a Venturi tube 26 which comprises a conical catch-nozzle portion tapering in the downstream direction and a pressure increasing conical nozzle space Widening in the downstream direction. The consumer steam passes out of the valve in the direction of the arrow 51 (to consumer line 7 in FIG. 1). The low-pressure steam to be converted to higher pressure passes into the second steam-inlet duct 54 of the valve in the direction of the arrow 27 (from line 5 and valve in FIG. 1).

The Venturi tube 26 extends in coaxial relation to the pressure-reducing throttle passage 21 and has a Venturi inlet opening wider than the outlet opening of the throttle passage 21. As a result, the second steam-inlet duct communicates with the Venturi tube 26 through the remaining annular gap and through an annular channel 52 which surrounds the passage-forming valve structure 53. The low-pressure steam entering through the inlet duct 54 is supplied to the fresh steam leaving the throttle passage 21 at high speed. The low-pressure steam is then raised to the desired consumer pressure in the Venturi nozzle tube with a simultaneous reduction in flow energy of the fresh steam.

The Venturi tube 26 is preferably designed as a separate component which is joined with the housing of the valve by means of flanges 55 and 56.

The known ejectors are generally operated with a constant fresheam quantity regulated by a throttle member ahead of the ejector. In a steam-converting ejector valve according to the invention, however, it is essential that, from the smallest steam quantity up to the applicable greatest quantity, an optimum degree of efiiciency is always attained. Accordingly, the present invention, as described above, combines the valve-control of the fresh steam with the fresh-steam quantity regulation and with the cooling and pressure reduction of the fresh steam in the fresh-steam nozzle passage. With such a design, the full fresh-steam pressure always obtains ahead of the narrowest cross section of the nozzle passage. Consequently, the pressure drop in the nozzle passage and the conversion into flow energy remain constant even though the steam quantity may vary.

The embodiment illustrated in FIG. 3 constitutes an improvement over that described above with reference to FIG. 2, corresponding components of the valve device being denoted by the same reference characters in all of FIGS. 2 through 6.

When in the modified valve according to FIG. 3 the valve stem 28 is axially lifted, the sealing disc 29 is removed from the valve seat 30. The high-pressure fresh steam can now pass from above beyond the slot 31 for the cooling water down to the narrowest location of the throttling nozzle passage 32. On this steam path the cooling water is atomized to an optimum degree. The throttle cone 20, extending coaxially with respect to valve stem 28 and valve disc 29 and tapering in the downstream direction within the widening inner surface 33 of the throttle passage, forms an annular reduction nozzle together with that passage. The regulation of the steam quantity is obtained by varying the narrowest throttle cross section at 32 in dependence upon the axial displacement of the valve stem 28. The full fresh-steam pressure always obtains ahead of the narrowest throttle cross section. Consequently the pressure drop in the nozzle passage and the conversion into fiow energy remain constant with variations in steam quantity.

The embodiment shown in FIG. 4 comprises a twinnozzle assembly which secures a particularly favorable nozzle shape at small fresh-steam quantities. When the valve stem 28 is being displaced axially, the first effect is to open the narrowest cross section between the tapering valve cone 34 and the widening annular throttle space formed between the cone and a tubular member 61. Member 61 is seated on stem 28 and axially displaceable relative thereto. After this narrowest cross section of the inner nozzle space is opened, an outer nozzle between the member 61 and the flaring bore of the nozzle structure 53 is opened. This takes place when the valve disc 36 abuts against a nut 37 in threaded engagement with the top of the displaceable member 61. The cooling water supplied through the water inlet duct 24 and the annular channel 25 passes through a narrow slot into the space between nozzle structure 53 and member 61. From channel 25 the water also passes through bores of member 61 into the space between member 61 and valve disc 36 at locations corresponding to those described above with reference to FIGS. 2 and 3. Consequently no essential change is involved in the embodiment of FIG. 4 relative to the cooling of the high-pressure steam.

In each of the above-described valves, the annular throttle nozzle varies its effective axial length in dependence upon the required lifting displacement of the valve stem. A condition less favorable from fluid-flow viewpoints, may occur if in a valve as shown in FIG. 2 the bottom edge of the valve cone 20 just lays open the narrowest cross section of the throttle passage 21. However the valve can be modified to remain favorable also under conditions of the just-mentioned type, such a modification being exemplified by the embodiment illustrated in FIGS. 5 and 6.

The illustrated portion of this valve, otherwise corresponding to those described above, constitutes a double throttling nozzle of rectangular shape Whose cross section is apparent from FIG. 6. In lieu of a rigid and fixed valve cone, as shown at 20 in FIG. 2, the valve of FIGS. 5 and 6 is provided with two nozzle limiting surface members 40 and 41 which are linked together at 40a and whose opposite edges are hinged to respective links 38 and 39 pivotally joined at 38a to the valve disc 29. When the valve stem 28 is being lifted, the first eflfect, as in the valves described above, is to raise the valve disc 29 off the seat 30. The links 38 and 39 then simultaneously act upon the respective surface members 40 and 41 to simultaneously turn them inwardly to the illustrated broken-line positions. With such a valve, the active nozzle length remain substantially the same over the entire steam throughput range, so that the nozzle has a favorable shape in fluid-flow respects for any steam quantity passing through.

It will be understood that for automatic control and regulating purposes as described above with reference to FIG. 1, the axial displacement of the valve stem 28 in the illustrated embodiments is preferably effected automatically under control by the pressure regulator 8 and under control by the temperature regulator 1 in accordance with the desired conditions of plant operation.

While, as described, an ejector-type conversion valve according to the invention is applicable for reducing and de-superheating high-pressure steam and simultaneously converting low-pressure steam to a desired higher pressure, it should be understood that ejector-type conversion valves according to the invention may also be employed in different ways. For example, the same valve may be used merely as a steam conversion valve. This is the case if no low-pressure steam to be converted to higher pressure is being supplied so that the only function desired of the valve is to reduce and cool fresh steam.

The novel steam ejector-type conversion valves may further be used to operate for pressure reduction purposes. With such an operation, too, no low-pressure steam to be converted to higher pressure is being supplied. The freshsteam temperature in this case is so low as to require no cooling.

Further use of valves according to the invention is for the purpose of merely cooling the steam to be increased in pressure. The pressure of the steam supplied to the above-described second steam-inlet duct must be sufliciently high in this case to require no pressure increase by fresh steam. The cooling can be effected by passing the cooling water in the direction of the arrow 23 (FIG. 2) through the line 24 into the annular channel 25 so that the cooling water and the steam become mixed in the Venturi tube 26. In each of these cases of modified use the one steam supply duct or the water supply duct not being used at a time may be closed.

It will be apparent to those skilled in the art, upon studying this disclosure, that ejector-type steam conversion valves according to our invention can be modified in various respects and hence may be given embodiments other than particularly illustrated and described herein, without departing from the esesntial features of the invention and within the scope of the claims annexed hereto.

We claim:

1. A steam conversion valve for pressure reduction and cooling of hot steam by throttling and water injection, comprising a valve housing provided with a first inlet duct for high-pressure hot steam from a fresh steam line, a second inlet duct for low-pressure steam withdrawn from a prime mover, and an outlet steam duct, nozzle means having a passage flaring outwardly in the direction of steam flow therethrough and positioned between said three ducts for passing hot steam from said first inlet duct to said outlet duct and for increasing the pressure of said withdrawn steam and passing the latter to said outlet duct, said outlet duct having a venturi tube coaxial with and communicating with said nozzle means, said second inlet duct having an annular channel surrounding said nozzle means and communicating with said venturi tube so that said nozzle means together with said annular channel and said venturi tube define jointly an ejector for driving steam through said outlet duct and for inducting said withdrawn steam in through said second inlet duct, whereby excess throttle energy inherent in the hot steam entering through said first inlet duct is utilized as a driving medium in the sense of a jet suction source for inducting said low-pressure steam through said second inlet duct and for increasing the pressure of the latter steam.

2. In a valve according to claim 1, said venturi tube having its end closest to said nozzle means of a diameter greater than said nozzle means to define an interspace therebetween, said annular channel communicating with said venturi tube through said interspace.

3. Steam conversion valve according to claim 1, further comprising means forming a water inlet within said nozzle means ahead of the narrowest cross section of said nozzle means in said flow direction.

4. Valve according to claim 3, said water inlet comprising an annular duct surrounding said outwardly flaring passage and communicating with the latter for evenly supplying cooling water to said passage.

5. A steam conversion valve according to claim 4, said nozzle means forming a valve seat and having a valve cone comprising a conical stem and a valve disc in coaxial relation to said nozzle passage and tapering toward the down-stream side whereby the active throttling flow cross section of said passage depends upon the distance said disc is moved ofi said seat.

References Cited in the file of this patent UNITED STATES PATENTS 224,798 Sellers Feb. 24, 1880 1,063,513 Cubelic June 3, 1913 1,194,312 Pape Aug. 8, 1916 1,821,206 Caswell Sept. 1, 1931 2,201,752 Winberg May 21, 1940 2,211,058 Guthmann Aug. 13, 1940 2,520,692 Powell Aug. 29, 1950 2,725,221 Pontow Nov. 29, 1955 FOREIGN PATENTS 226,864 Italy Aug. 16, 1929 698,804 Germany Nov. 18, 1940 855,656 Germany Nov. 13, 1952 531,777 Italy Aug. 5, 1955 

1. A STEAM CONVERSION VALVE FOR PRESSURE REDUCTION AND COOLING OF HOT STEAM BY THROTTLING AND WATER INJECTION, COMPRISING A VALVE HOUSING PROVIDED WITH A FIRST INLET DUCT FOR HIGH-PRESSURE HOT STEAM FROM A FRESH STEAM LINE, A SECOND INLET DUCT FOR LOW-PRESSURE STEAM WITHDRAWN FROM A PRIME MOVER, AND AN OUTLET STEAM DUCT, NOZZLE MEANS HAVING A PASSAGE FLARING OUTWARDLY IN THE DIRECTION OF STEAM FLOW THERETHROUGH AND POSITIONED BETWEEN SAID THREE DUCTS FOR PASSING HOT STEAM FROM SAID FIRST INLET DUCT TO SAID OUTLET DUCT AND FOR INCREASING THE PRESSURE OF SAID WITHDRAWN STEAM AND PASSING THE LATTER TO SAID OUTLET DUCT, SAID OUTLET DUCT HAVING A VENTURI TUBE COAXIAL WITH AND COMMUNICATING WITH SAID NOZZLE MEANS, SAID SECOND INLET DUCT HAVING AN ANNULAR CHANNEL SURROUNDING SAID NOZZLE MEANS AND COMMUNICATING WITH SAID VENTURI TUBE SO THAT SAID NOZZLE MEANS TOGETHER WITH SAID ANNULAR CHANNEL AND SAID VENTURI TUBE DEFINE JOINTLY AN EJECTOR FOR DRIVING STEAM THROUGH SAID OUTLET DUCT AND FOR INDUCTING SAID WITHDRAWN STEAM IN THROUGH SAID SECOND INLET DUCT, WHEREBY EXCESS THROTTLE ENERGY INHERENT IN THE HOT STEAM ENTERING THROUGH SAID FIRST INLET DUCT IS UTILIZED AS A DRIVING MEDIUM IN THE SENSE OF A JET SUCTION SOURCE FOR INDUCTING SAID LOW-PRESSURE STEAM THROUGH SAID SECOND INLET DUCT AND FOR INCREASING THE PRESSURE OF THE LATTER STEAM. 